Laminar flow sluice concentrator



May 5, 1970 w. B. TOMLINSON Filed Nov. 25, 1968 I N VENTOR WILLIAM B.TOMLINSON 41 604w, dwww #W XQ.

ATTORNEYS United States Patent 3,509,997 LAMINAR FLOW SLUICECONCENTRATOB William B. Tomlinson, Fernandina Beach, Fla., asslgnor toCarpco Research & Engineering, Inc., Jacksonville, Fla., a corporationof Florida Filed Nov. 25, 1968, Ser. No. 778,446 Int. Cl. B03b 3/04 U.S.Cl. 209458 14 Claims ABSTRACT OF THE DISCLOSURE A sluice concentratoradapted to separate particulate materials of different specificgravities which are suspended in a feed slurry. The concentratorincludes at least one sluice section and a means for feeding an even andtranquil flow of the slurry thereto. The sluice section includes a firstportion defining means for initiating a laminar flow of the slurry andconverging the flow, to thereby increase the depth and velocity of theslurry and efficiently stratify the materials into a plurality ofstrata; a second portion defining means for maintaining the laminar flowof the slurry and diverging the flow, to thereby decrease the depth andvelocity of the slurry and evenly spread the strata; and a dischargemeans for removing a fraction of the stratified material from theconcentrator.

BACKGROUND OF THE INVENTION Field of the invention This inventionrelates to sluice concentrators, and more particularly to a sluiceconcentrator that is specifically adapted to separate a desiredparticulate material from a mixture of particulate materials in whichother mterials are present having specific gravities similar to that ofthe desired material and in which the desired material is present invery small quantities.

Description of the prior art A well-known phenomenon occurs when aliquid in which particulate materials of different specific gravitiesare suspended, i.e., a slurry of such materials, is permitted to flow ina relatively tranquil state through a conduit. The particulate materialsstratify into a plurality of strata according to their relative specificgravities; the material of greatest specific gravity being on the bottomand the material of least specific gravity being on the top, with thematerials of intermediate specific gravities being arrangedtherebetween.

This phenomenon has been used advantageously for separating minerals ofdifferent specific gravities. Generally, a tapered sluice concentratoris provided, through which a substantialy laminar flow of a slurry ofthe minerals to be separated is directed. In the presence of the laminarflow, the mineral particles arrange themselves, under the influence ofgravity, into strata according to their specific gravities. Further, andas taught in French Pat..1,771,081, an increase in the depth andvelocity of the slurry tends to accelerate the rate of Stratification.

However, conventional tapered sluice concentrators of this type have notprovide suitable for separating finely divided mineral particles ofsimilar specific gravities because the velocity of the slurry cannot beincreased sufficiently to stratify the minerals efficiently withoutdisrupting the laminar flow. Thus, in such concentrators, as the flowrate is increased the slurry tends to ripple along the concentratorsidewalls, introducing turbulence into the flow. Such turbulence tendsto intermingle the suspended mineral particles and thus impedeStratification.

3,509,997 Patented May 5, 1970 SUMMARY OF THE INVENTION The sluiceconcentrator of the invention provides a solution to the aforementioneddifficulty associated with conventional tapered sluice concentrators,and is particularly adapted for separating finely divided minerals ofsimilar specific gravities.

Basically described, the concentrator of the invention includes a sluicesection that is adapted to receive a slurry of the materials to beseparated. The sluice section includes; a first portion which definesmeans for initiating a laminar flow of the slurry and converging saidflow, to thereby increase the depth and velocity of the slurry andstratify the materials into a plurality of strata according to theirspecific gravities; a second portion contiguous with said first portionwhich defines means for maintaining the laminar flow of the slurry anddiverging said flow, to thereby decrease the depth and velocity of theslurry and evenly spread the strata; and a discharge means disposedadjacent the second portion for removing a fraction of the stratifiedmaterials from the concentrator. The concentrator also includes a feedmeans associated with the sluice section for feeding an even flow of theslurry to the first portion of the sluice section.

Preferably, the concentrator further includes at least one additionalsluice section which is contiguous with the above-mentioned firstsection and which is adapted to receive the slurry after it has passedthrough the first section. The additional sluice section is structurallysimilar to the first section; including a first portion which definesmeans for maintaining the laminar flow of the slurry and reconvergingsaid flow, to thereby again increase the depth and velocity of theslurry and restratify the materials into a plurality of strata accordingto their specific gravities after the above-mentioned first fraction isremoved therefrom; a second portion contiguous with said first portionwhich defines means for maintaining the laminar flow of the slurry andrediverging said flow, to thereby again decrease the depth and velocityof the slurry and again evenly spread the strata; and an additionaldischarge means disposed adjacent the second portion of the additionalsluice section for removing an additional fraction of the stratifiedmaterials from the concentrator.

Accordingly, it is an object of the invention to provide a laminar flowsluice concentrator that is adapted to separate particulate materials ofdifferent specific gravities.

It is also an object of the invention to provide a laminar flow sluiceconcentrator that is specifically adapted to efficiently separate finelydivided minerals of different specific gravities.

It is a further object of the invention to provide a sluice concentratorhaving a sluice section that is characterized by first and secondportions which converge and diverge, respectively, a flow of a slurry ofparticulate materials, while initiating and maintaining such flow in alaminar condition.

It is an additional object of the invention to provide a laminar flowsluice concentrator having means for feeding an even and tranquil flowof a slurry of particulate materials to a sluice section.

These and other objects of the invention will become apparent upon aconsideration of the detailed description of a preferred embodimentthereof given in connection With the following drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of theconcentrator of the invention;

FIG. 2 is an elev-ational view, partially in section, of theconcentrator shown in FIG. 1;

3 FIG. 3 is a vertical sectional view of the concentrator shown in FIG.1;

FIG. 4 is a sectional view taken along line 44 of FIG. 3; and

FIG. 5 is an enlarged vertical sectional view of a portion of theconcentrator shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of theconcentrator of the invention is shown in FIGS. 1 and 2, as designatedby reference numeral 10. Concentrator includes a conduit 16 defining afirst sluice section 12, a second sluice section 14 and a third sluicesection 15; the feed end of second section 14 being contiguous with thedischarge end of first section 12 and the feed end of third section 15being contiguous with the discharge end of second section 14. Conduit 16comprises a pair of opposed, converging, continuous sidewalls 18 and acontinuous bottom wall 20, and is supported by a plurality of legs 22.Legs 22 support the conduit in an inclined attitude so that a slurry ofparticulate materials introduced into the upper or feed end 21 thereofwill flow down the conduit and be discharged therefrom at the lower ordischarge end 23 thereof. Concentrator 10 also includes a feed means 24for introducing the slurry into first sluice section 12. The feed meansis descibed in detail below.

A flow guide 26 is connected to the inside surface of each sidewall 18along the section of conduit 16 defining first sluice section 12. Theflow guides preferably are connected to the sidewalls by adjustablemeans which permit the position of the guides to be regulatedlongitudinally of conduit 16. .Such means conveniently comprise slots 17formed in sidewalls 18 within which are accommodated threaded studs 19afifixed to flow guides 26. The studs are locked in position by nuts 25.

The insidesurface of each of flow guides 26 is defined by an inwardlycurved segment 28 and an outwardly curved segment 30. Each inwardlycurved segment is contiguous with the associated outwardly curvedsegment and forms therewithv a continuous unbroken convex curve.

Bottom wall and inwardly curved segments 28 form a first portion 32 offirst sluice section 12. First portion 32 defines means for initiating alaminar flow of the slurry introduced therein and converging such flow.Convergence of the flow causes the depth and velocity of the slurry toincrease. In the presence of the laminar flow, these conditions inducethe particulate materials in the slurry to stratify, under the influenceof gravity, into a plurality of strata according to their relativespecific gravities.

Bottom wall 20 and outwardly curved segments form a second portion 34 offirst sluice section 12. Second portion 34 defines means for maintainingthe laminar flow of the slurry'and diverging such flow. Divergence ofthe flow causes the depth and velocity of the slurry to decrease. In thepresence of the laminar flow, these conditions induce the strata ofparticulate materials to spread laterally of the flow across the surfaceof bottom wall 20.

First sluice section 12 also includes a discharge means 36 disposedadjacent second portion 34 for removing a fraction of the stratifiedparticulate materials from the concentrator. The discharge meanscomprises a plate 38 which is removably insertable into a recess 40(FIG. 5) in bottom wall 20, and which preferably is located near thejunctures of outwardly curved segments 30 and the inside surfaces ofsidewalls 18. Plate 38 may be made of a plastic material, such aspolyvinyl chloride, or any other suitable material, and has a transverseslot 42 therein which overlies a transverse slot 44 in bottom wall 20. Afraction of the stratified particulate materials passes through slots 42and 44 as the slurry flows thereover, and may be separately collectedbelow conduit 16. Since plate 38 is removable, other similar plateshaving slots of diiferent shapes and dimensions can be substituted forplate 38 as required for reasons discussed in detail below.

Second sluice section 14 commences at discharge means 36. A flow guide39 is connected to the inside surface of each sidewall 18 along theportion of conduit 16 defining sluice section 14. If desired, flowguides 39 may be connected to sidewalls 18 by adjustable means whichpermit the position of the flow guides to be regulated longitudinally ofconduit 16, as described above in connection with flow guides 26.

Flow guides 39 are structurally similar to flow guides 26 and form withbottom wall 20 a first portion 41 and a second portion 43. First portion41, similarly to first portion 32, defines means for maintaining thelaminar flow of the slurry introduced into the feed end of section 14from the discharge end of section 12 and reconverging such flow.Reconvergence of the flow causes the depth and velocity of the slurry toagain increase, thereby inducing the particulate materials in the slurryto restratify after the first faction has been removed therefrom. Secondportion 43, similarly to second portion 34, defines means formaintaining the laminar flow of the slurry and rediverging such flow.Redivergence of the flow causes the depth and velocity of the slurry toagain decrease, thereby inducing the particulate materials in the slurryto again spread laterally across the surface of bottom wall 20.

Second sluice section 14 also includes a discharge means 46, which isstructurally similar to discharge means 36, for removing a secondfraction of the stratified particulate materials from the concentrator.Discharge means 46 preferably is located near the lower junctures 45 offlow guides 39 and the inside surfaces of sidewalls 18.

Third sluice section 15 commences at discharge means 46, and includes apair of flow guides 47, which are structurally similar to flow guides 26and 39, and a discharge means 48 which is structurally similar todischarge means 36 and 46. A third fraction of the stratifiedparticulate materials is removed from the concentrator by dischargemeans 48.

Conduit 16 extends downwardly a short distance beyond third sluicesection 15, which terminates at discharge means 48, to discharge end 23.The fraction of the particulate materials not removed by discharge means36, 46 and 48 flows out of conduit 16 at discharge end 23.

To promote the laminar flow of the slurry down conduit 16, the insidesurfaces of sidewalls 18, bottom wall 20, and flow guides 26, 39 and 47are made so smooth as is economicaly feasible, such as by coating suchsurfaces with a durable plastic material, thereby reducing boundarylayer turbulence along the surfaces of the conduit contacted by theslurry.

Feed. means 24 includes a receptacle 50 which is positioned above feedend 21 and which comprises a plurality of sidewalls 52, 54, 56 and 58,and a bottom wall 60. Receptacle 50 has an open top through which acontinuous supply of the slurry of particulate materials to be separatedis introduced therein. The receptacle has at least one port, andpreferably a plurality of ports 62, opening therefrom above bottom Wall60. As shown in FIG. 4, ports 62 preferably comprise a plurality ofhorizontally spaced circular openings in sidewall 56; the latter beingdisposed transversely of conduit 16.

As shown in FIG. 3, when a head of the slurry is established inreceptacle 50 the slurry flows out of ports 62 into feed end 21. Thisarrangement has at least two beneficial effects. First, an even flow ofthe slurry is introduced into the conduit irrespective of the feed rateof the slurry into receptacle 50. Second, any foreign matter, such astwigs, rocks, or the like, contained in the slurry either falls to thebottom of the receptacle 50' or floats on the surface of the headestablished therein. In either event the foreign matter does not clog orpass through ports 62 and therefore does not affect the flow of theslurry into and down conduit 16.

Feed means 24 also includes a baflle 63 disposed transversely ofconduit. 16 and interposed between receptacle 50 and first portion 32 offirst sluice section 12.'Bafl le 63 has a rectangular cutout thereinwhich is positioned adjacent bottom wall 20 and defines therewith arelatively narrow transverse opening 65, through which the slurry flowsfrom feed end 21 into first portion 32. Any turbulence generated by thepassage of the slurry from receptacle 50 into feed end 21 is suppressedby the passage of the slurry through opening 65. Baflle 63 thus insuresthat a relatively tranquil flow of the slurry will pass into firstportion 32.

Concentrator is specifically adapted to separate finely divided mineralsof diflferent specific gravities. And in particular, the concentratorhas proven extremely efficient for separating a desired heavy mineralfrom mixtures in which other minerals are present having specificgravities similar to that of the desired mineral and in which thedesired mineral is present in very small quantities. An example of sucha desired heavy mineral is monazite, an ore of cerium and thorium.Monazite has a specific gravity of 5.0, and frequently is found inmixtures containing ilmenite, specific gravity 4.7; zircon, specificgravity 4.68; garnet, specific gravity 4.3; rutile, specific gravity4.25; staurolite, specific gravity 3.75; kyanite, specific gravity 3.66and other minerals of lesser specific gravities. It is not economicallyfeasible to separate the monazite from the concentrator. It has beenfound that when concentrator 10 is utilized for separating monazite froma mixture of minerals similar to that described above, a single passthrough the concentrator is sufficient to reduce the amount of monaziteremaining in the tailings fraction to a minimal percentage. Thus, afinal tailings is obtained in a single pass.

EXAMPLE Two samples of monazite ore were separated utilizing aconcentrator similar to concentrator 10. For the first sample, the flowguides were removed from the concentrator and for the second sample theflow guides were installed as described above. Both samples containedless than 4.0 percent monazite. The separation results are shown inTable 1 below.

the other minerals comprising this mixture utilizing conventionaltapered sluice concentrators. This deficiency derives from the fact thatthe specific gravities of the minerals comprising the mixture are ofsimilar values. Thus, if the velocity of a slurry containing such amixture is increased sufiiciently to obtain the desired stratificationit is virtually impossible to maintain a laminar flow of the slurry inconventional tapered sluice concentrators. Concentrator 10 overcomesthis deficiency.

In operation, a continuous supply of a slurry of a mixture of theminerals to be separated is introduced into receptacle 50 and a head ofthe slurry established therein (FIG. 3). From receptacle 50 the slurryfiows through ports 62 into feed end 21 and through bafile opening 65into first portion 32 of first sluice section 12.

As the slurry commences flowing through first portion 32, laminar flowcondition is achieved almost immediately. The flow is then convergedsmoothly as it passes through the zone defined by portion 32 so that thedepth and velocity of the slurry are gradually increased. As thisoccurs, the mineral particles are elficiently stratified according totheir different specific gravities with the desired heavy mineral, suchas monazite, comprising the lower-most strata.

The slurry then passes into the second portion 34 of first sluicesection 12 where the laminar flow condition of the slurry is maintainedand the flow diverged smoothly as the flow passes through the zonedefined by portion 34. As a result of this divergence, the depth andvelocity of the slurry is decreased so that the strata of mineralparticles are slowed down and spread evenly across the width of bottomwall 20. These conditions facilitate the removal of a concentratesfraction by discharge means 36.

The initial convergence of the flow promotes the recovery of a highgrade concentrates fraction and the subsequent divergence of the flowpromotes a high recovery rate of such fraction.

After passing discharge means 36, the slurry flows successively throughsecond and third sluice sections 14 and 15. As the slurry flows througheach of sluice sec- The results shown in Table 1 indicate that the flowguides improved the grade of the concentrates fraction by 7.2 percent,an economically significant increase.

As mentioned above plate 38 may be removed from recess 40 and replacedby a similar plate having a slot therein of a different shape anddimensions than slot 42. Similarly, the plates of discharge means 46 and48 may be replaced by other plates having slots of different shapes anddimensions therein. Obviously, the wider the slot in a particular plate,the greater will be the amount of mineral particles removed from theconcentrator by the discharge means in which such plate is employed.This permits the grade and recovery rate of the separated fractions tobe accurately controlled.

Concentrator 10 comprises an eflicient and relatively inexpensive meansfor separating particulate materials of different specific gravities,and in particular for separating a desired heavy mineral from a mixtureof finely divided mineral particles in which other minerals havingspecific gravities similar to that of the desired mineral are present.

While the foregoing constitutes a detailed description of a preferredembodiment of the invention, it is recognized that various modificationsthereof will occur to those skilled in the art. Therefore, the scope ofthe invention is to be limited solely by the scope of the claimsappended hereto.

I claim:

1. A concentrator for separating particulate materials of differentspecific gravities comprising:

a conduit having an upper feed end and a lower discharge end;

a feed means associated with said conduit for feeding an even flow of aslurry of the materials to be separated into said feed end, said feedmeans including turbulence suppression means for promoting a tranquilflow of the slurry from said feed end; and

at least one sluice section defined by said conduit and adapted toreceive the slurry from said feed end,

said sluice section including a first portion defining means forinitiating and maintaining a laminar flow of the slurry therethrough andconverging said flow, thereby increasing the depth and velocity of theslurry and stratifying the materials into a plurality of strataaccording to the different specific gravities thereof, a second portioncontiguous with said first portion, said second portion defining meansfor maintaining the laminar flow of the slurry therethrough anddiverging said flow, thereby decreasing the depth and velocity of theslurry and evenly spreading said strata, and a discharge means disposedadjacent said second portion for removing a fraction of the stratifiedmaterials from the concentrator.

2. A concentrator for separating particulate materials of differentspecific gravities as recited in claim 1, wherein said first and secondportions are formed by said conduit and a pair of opposed continuousflow guides.

3. A concentrator for separating particulate materials of differentspecific gravities as recited in claim 2, wherein said flow guides arecurved inwardly along said first portion and are curved outwardly alongsaid second portion.

4. A concentrator for separating particulate materials of differentspecific gravities as recited in claim 2, wherein said flow guides areadjustable longitudinally of said conduit.

5. A concentrator for separating particulate materials of differentspecific gravities as recited in claim 1, wherein said discharge meanscomprises a transverse slot in said conduit.

6. A concentrator for separating particulate materials of differentspecific gravities as recited in claim 1, further comprising:

a second sluice section defined by said conduit and contiguous with saidfirst-mentioned section, said second sluice section being adapted toreceive the slurry after it has passed through said first section andincluding a first portion defining means for maintaining the laminarflow of the slurry therethrough and reconverging said flow, therebyagain increasing the depth and velocity of the slurry and restratifyingthe materials into a plurality of strata according to the differentspecific gravities thereof after said firstmentioned fraction is removedtherefrom, a second portion defining means for maintaining the laminarfiow of the slurry therethrough and rediverging said flow, thereby againdecreasing the depth and velocity of the slurry and again evenlyspreading said strata, and a second discharge means disposed adjacentsaid second portion of said second section for removing a secondfraction of the stratified materials from the concentrator.

7. A concentrator for separating particulate materials of differentspecific gravities as recited in claim 6, further comprising:

a third sluice section defined by said conduit and contiguous with saidsecond section, said third sluice section being adapted to receive theslurry after it has passed through said second section and including afirst portion defining means for maintaining the laminar flow of theslurry therethrough and reconverging said fiow, thereby again increasingthe depth and velocity of the slurry and restratifying the materialsinto a plurality of strata according to the different specific gravitiesthereof after said second fraction is removed therefrom, a secondportion defining means for maintaining the laminar flow of the slurryand rediverging said flow, thereby again decreasing the depth andvelocity of the slurry therethrough and again evenly spreading saidstrata, and a third discharge means disposed adjacent said secondportion of said third section for removing a third 8 fraction of thestratified materials from the concentrator.

8. A concentrator for separating particulate materials of differentspecific gravities as recited in claim 7, wherein said first and secondportions of each of said first, second and third sluice sections areformed by said conduit and a pair of opposed continuous flow guides.

9. A concentrator for separating particulate materials of differentspecific gravities as recited in claim 8, wherein said flow guides arecurved inwardly along said first portion'of each of said first, secondand third sections and are curved outwardly along said second portion ofeach of said sections.

10. A concentrator for separating particulate materials of differentspecific gravities as recited in claim 1, wherein said feed meansincludes a receptacle for receiving a continuous supply of the slurry,said receptacle having at least one port opening therefrom above thebottom thereof, said port being positioned above said feed end so that ahead of the slurry will be established within the receptacle and theslurry will be discharged therefrom through said port in an even flowinto the feed end.

11. A concentrator for separating particulate materials of differentspecific gravities as recited in claim 10, wherein said receptacleincludes a plurality of walls, at least one of which is disposedtransversely of said conduit; and wherein said port comprises an openingin said one wall.

12. A concentrator for separating particulate materials of differentspecific gravities as recited in claim 11, wherein said receptacle has aplurality of ports opening therefrom comprising a plurality ofsubstantially horizontally spaced openings in said one wall.

13. A concentrator for separating particulate materials of differentspecific gravities as recited in claim 10, wherein said turbulencesuppressing means comprises a baffle disposed transversely of saidconduit and interposed between said receptacle and said first portion,said baffle having a cutout therein and defining with said conduit anopening through which the slurry flows from said feed end to saidfirstportion.

14. A process for separating particulate materials of differentgravities comprising the successive steps of:

initiating a laminar flow of a slurry of the materials to be separated;

converging said flow as the flow passes through a first zone whilemaintaining the flow in a laminar condition, thereby increasing thedepth and velocity of the slurry and stratifying the materials into aplurality of strata according to the different specific gravitiesthereof;

immediately thereafter diverging said flow as the flow passes through asecond zone while maintaining the flow in a laminar condition, therebydecreasing the depth and velocity of the slurry and evenly spreadingsaid strata; and

immediately thereafter removing a fraction of the stratified materialsfrom the slurry.

References Cited UNITED STATES PATENTS 189,928 4/1877 Evans 209---4581,704,185 3 /1929 France 209-458 1,771,081 7/ 1930 France 209-4582,171,674 9/1939 Schifferle 209157 FRANK W. LUTTER, Primary Examiner US.Cl. X.R. 209-497

